[vlc-devel] commit: Do not refuse to open odd port number with RTP input access. ( Laurent Aimar )

[Rémi Denis-Courmont]

Le dimanche 23 novembre 2008 13:04:28 Laurent Aimar, vous avez écrit :
> > This breaks when parsing an SDP (currently from the SAP SD) with an odd
> > port.
>
>  The sdp parser could make it even then.
> But I am curious, did you see SDP advertizing odd port when they mean even
> ? (maybe it is describe in the RFC)

The standard alrogithm for the Audio Video Profile, where p is the SDP media 
line port, is:
- RTP on the first even port from p,
- RTCP on the first odd port from p.

In other words, AVP is always using p and p + 1, and always has RTP resp RTCP 
on the even resp odd port of the pair. There is no arguing that this is 
conter-intuitive, if not inflexible. I actually believe that most such 
instances of an odd p value are configuration errors that go unnoticed so 
long as both senders and receivers follow the same algorithm. But it does 
happen anyway. Other senders and receivers do follow the specification, and 
breaking IOP with standard-compliant peers is a bad idea.

-- 
Rémi Denis-Courmont
http://git.remlab.net/cgi-bin/gitweb.cgi?p=vlc-courmisch.git;a=summary